The present invention relates to a gate structure of a MOS type field effect transistor (FET).
A MOS FET has an oxide layer on a silicon substrate thereof, and a gate electrode on the oxide layer. A conventional gate electrode is formed of, e.g., polycrystalline silicon resistant to high-temperature treatment. In this case, the gate electrode has relatively high resistivity, which degrades the frequency characteristics of the MOS FET. In other words, with the conventional MOS FET structure, high power gain cannot be obtained within the high-frequency band above the VHF band.